Domain Multiple inheritance and manyToMany relation removeFrom not working - grails

Question

I prepared some complex model structure due to content management businnes.
My main content model likes as following code.
class CmsContent implements Comparable<CmsContent>, Taggable, Serializable {
Set<CmsContent> contents
static hasMany = [contents:CmsContent]
}
Other Content Model extends from above
class Menu extends CmsContent {
}
class Image extends CmsContent {
}
class Video extends CmsContent {
}
On Controller side when ever add Image to Menu it is perfectly working
def addContent(){
Menu menuInstance = Menu.get(params.id)
if (menuInstance == null) {
notFound()
return
}
CmsContent content = CmsContent.get(params.contentId)
if (content == null) {
notFound()
return
}
menuInstance.addToContents(content)
menuInstance.save(flush: true)
request.withFormat {
'*'{
def result =[:] ;
result.status ='success';
render result as JSON
}
}
}
def removeContent(){
Menu menuInstance = Menu.get(params.id)
if (menuInstance == null) {
notFound()
return
}
long id = Long.valueOf(params.contentId)
CmsContent content = cmsContent.contents.find { it.id == id }
if (content == null) {
notFound()
return
}
menuInstance.removeFromContents(content)
menuInstance.save(flush: true)
request.withFormat {
'*'{
def result =[:] ;
result.status ='success';
render result as JSON
}
}
}
But when I tried to remove facing following exception.
Cannot get property 'name' on null object. Stacktrace follows:
Message: Cannot get property 'name' on null object
I tracked down in grails code in DomainClassGrailsPlugin.
I realize that addTo Method and line 368 checking prop.otherSide attribute
if (prop.bidirectional && prop.otherSide) {
}
unfortunately removeTo method not check prop.otherSide attribute, therefore name field throwing the exception.
if (prop.bidirectional) {
if (prop.manyToMany) {
String name = prop.otherSide.name
arg[name]?.remove(delegate)
} else {
arg[prop.otherSide.name] = null
}
}
What do you think ? Do you agree with me ?